Criminal Investigation

The application of stable isotope analysis in the criminal forensics brings unique capabilities to the modern day crime laboratory. Harnessing the power of the unique stable isotope fingerprint makes it possible to determine similarities between different drug seizures and so follow trafficking routes back to their original clandestine source. The same principle can be applied to other criminal materials such as explosives or counterfeit money and goods. Stable isotopes can also be utilised to put unidentified corpses in to geographical context by comparing the stable isotope fingerprint of hair, bone, tooth and nails with known databases to evaluate the life history of the victim.

Criminal forensics publications using our instruments

Our customers use our instruments to do some amazing research in the criminal application field. To show you how they perform their research and how they use our IRMS instruments, we have collected a range of peer-reviewed publications which cite our products. You can find the citations below and then follow the links to the publishing journal should you wish to download the publication.

If you would like to investigate our available citations in more detail, or email the citation list to yourself or your colleagues then take a look at our full citation database.

Classification of nine malathion emulsion samples by using carbon isotope ratios and the ratio of organic solventsScience & Justice (2016)

Nana Suto, Hiroto Kawashima

The compound specific isotope analysis is nowadays an important and powerful tool in geochemical, environmental and forensics field. On November 2013, Aqli Foods Corporation in Japan dealt with complaints about stench from frozen foods produced. Subsequently, very high concentrations of organophosphorus pesticide as malathion, ethylbenzene and xylene were detected in recovered frozen foods. In particular case, we present the method to measure the stable carbon isotope ratio (δ13C) of nine malathion emulsion pesticides using gas chromatography/isotope ratio mass spectrometry (GC/IRMS) to identify the source. The δ13C values of malathion ranged from −30.6‰ to −29.5‰. Because malathion used in all malathion emulsions sold in Japan is imported from the same overseas company, Cheminova, Denmark. The δ13C values of ethylbenzene ranged from −28.2‰ to −20.8‰ and those of m,p-xylene from −28.7‰ to −25.2‰. The differences in the δ13C values may be because of the material itself and chemical processing. We also determined the ratio of ethylbenzene to m,p-xylene and finally categorized the nine malathion samples into five groups on the basis of this ratio and the δ13C values of ethylbenzene and m,p-xylene. The results of isotopic fractionation during volatilization (refrigerate, room temperature and incubator) was negligible small.

RATIONALE: Natural stable carbon (δ(13)C) and nitrogen isotope ratios (δ(15)N) of humans are related to individual dietary habits and environmental and physiological factors. In forensic science the stable isotope ratios of human remains such as hair and nail are used for geographical allocation. Thus, knowledge of the global spatial distribution of human δ(13)C and δ(15)N values is an essential component in the interpretation of stable isotope analytical results. METHODS: No substantial global datasets of human stable isotope ratios are currently available, although the amount of available (published) data has increased within recent years. We have herein summarised the published data on human global δ(13)C andδ(15)N values (around 3600 samples) and added experimental values of more than 400 additional worldwide human hair and nail samples. In order to summarise isotope ratios for hair and nail samples correction factors were determined. RESULTS: The current available dataset of human stable isotope ratios is biased towards Europe and North America with only limited data for countries in Africa, Central and South America and Southeast Asia. The global spatial distribution of carbon isotopes is related to latitude and supports the fact that human δ(13)C values are dominated by the amount of C4 plants in the diet, either due to direct ingestion as plant food, or by its use as animal feed. In contrast, the global spatial distribution of human δ(15)N values is apparently not exclusively related to the amount of fish or meat ingested, but also to environmental factors that influence agricultural production. CONCLUSIONS: There are still a large proportion of countries, especially in Africa, where there are no available data for human carbon and nitrogen isotope ratios. Although the interpretation of modern human carbon isotope ratios at the global scale is quite possible, and correlates with the latitude, the potential influences of extrinsic and/or intrinsic factors on human nitrogen isotope ratios have to be taken into consideration.

Christine Lehn, Andreas Rossmann, Matthias Graw

Stable isotopemethods can be used to determine the provenance of unidentified corpses. Body tissue materials such as teeth, bone, hair and nail taken frommortal remains provide information of different time periods of an individuals' life from childhood to death. Tissues of newborns contain provenance information of different time periods during pregnancy of the child's mother. The results of stable isotope analyses of body residues of two adults and a newborn found in Germany between 2010 and 2012 are presented. To determine the geographic origin and movements of unknown individuals, stable isotopes of hydrogen, carbon, nitrogen and sulphur were analysed in hair and bone collagen samples. Amino acid composition and, as a consequence, δ2H, δ13C, δ15N, and δ34S values in human keratin and bone collagen are different. Consequently correction factorswere determined to compare isotopic data of bone colla- gen with those of an extensive worldwide reference hair collection. The isotopic signatures in hair and in bone collagen samples were compared to geographical groups of reference hair samples by canonical discriminant analysis. The results served as the basis for providing provenance constraints for the unidentified persons as requested by the police and prosecution. Ultimately the individuals were identified; hence the isotopic prove- nance interpretations can be critically evaluated and are shown to be successful

Christine Lehn, Christina Lihl, Andreas Roßmann

To receive information about the duration of a person’s stay abroad related to those questions in forensics, stable isotopes of H–C–N–S were analysed in beard hair samples from four young soldiers, who went from Fürstenfeldbruck (Bavaria, Germany) to Phoenix (Arizona, USA) on the same date for their pilot training over a time period of 3 months. All study subjects were almost of the same age, had similar physical constitutions and stayed at the same military bases for the whole study period. However, the results showed considerable individual variabilities. In Arizona, hair δ13C increased by 2.3‰(±0.6) and δ34S decreased by 1.8‰(±1.2). No remarkable shifts of hair δ15Nand δ2H were observed. Significant shifts of δ13Cor δ34S in the shaved beard hair samples occurred 8 or 9 days after arrival in Arizona, respectively. The time lag to receive the isotope signals in hair due to US diet correspond to the growth period that hair needs to cover the distance of 2–3 mmfrom its root to the surface of the skin. This implies that isotopic changes due to the consumption of food and drinks were incorporated almost immediately into the hair protein. Consequently, if connected with an isotopic change of the diet, short-term stays for only a few days might be clearly recognizable within the first millimetres of a scalp hair strand which includes the hair roots.

Using stable isotope analysis to discriminate gasoline on the basis of its origin.Rapid communications in mass spectrometry : RCM (2012)

Su-Young Heo, Woo-Jin Shin, Sin-Woo Lee, Yeon-Sik Bong, Kwang-Sik Lee

RATIONALE: Leakage of gasoline and diesel from underground tanks has led to a severe environmental problem in many countries. Tracing the production origin of gasoline and diesel is required to enable the development of dispute resolution and appropriate remediation strategies for the oil-contaminated sites. METHODS: We investigated the bulk and compound-specific isotopic compositions of gasoline produced by four oil companies in South Korea: S-Oil, SK, GS and Hyundai. The relative abundance of several compounds in gasoline was determined by the peak height of the major ion (m/z 44). RESULTS: The δ(13)C(Bulk) and δD(Bulk) values of gasoline produced by S-Oil were significantly different from those of SK, GS and Hyundai. In particular, the compound-specific isotopic value (δ(13)C(CSIA)) of methyl tert-butyl ether (MTBE) in S-Oil gasoline was significantly lower than that of gasoline produced by other oil companies. The abundance of several compounds in gasoline, such as n-pentane, MTBE, n-hexane, toluene, ethylbenzene and o-xylene, differed widely among gasoline from different oil companies. CONCLUSIONS: This study shows that gasoline can be forensically discriminated according to the oil company responsible for its manufacture using stable isotope analysis combined with multivariate statistical analysis.

In this study, headspace single-drop microextraction (HS-SDME) coupled with gas chromatography–isotope ratio mass spectrometry (GC–IRMS), was employed to determine compound specific carbon isotopic values (δ13C) of gasoline range hydrocarbons. The reproducibility of the method was found to be satisfactory. By comparison with the δ13C values of the twelve target compounds determined using direct injection of their n-C16 solution, no obvious isotopic fractionation was observed during the HS-SDME procedures. Some parameters that could affect the carbon isotopic fractionation, such as ionic strength of working solutions and inlet split ratio, were examined. The results also suggest that these factors had no significant effect on the carbon isotopic determination of gasoline range hydrocarbons. The application of HS-SDME to a crude oil sample proved that this method could be a promising tool for the determination of carbon isotopic values of gasoline range hydrocarbons in oils or aqueous samples.

Christine Lehn, Elisabeth Mützel, Andreas Rossmann

This paper presents a comparison of the isotopic ratios of hydrogen, carbon, nitrogen and sulphur of three pairings of hair and nail tissue taken from contemporary human remains. Our aim was to examine the possibility of a direct comparison of isotopic data in hair with that of nail tissue for forensic purposes. The results indicate that stable isotope ratios of the elements were best comparable between human scalp hair longer than 3 cm and the distal end of the nails. There were no distinct variations between finger and toenails. Our isotopic data for bulk hair and nail confirmed that hair samples were slightly enriched in (13)C but depleted in (15)N compared to nail samples. Furthermore, our data reveal that δ(34)S values in nail samples were more variable than in hair samples. Direct comparison of the corresponding segments of hair and nail samples may be difficult due to individual differences especially for δ(15)N and δ(2)H. Hair may have an isotopic composition more consistent with the ingested food within a specific time than is provided by nail. It can be concluded that once a hair is formed, no further metabolic changes of the isotopic pattern should occur. Nevertheless, our data suggest that there was a change in isotope ratios particularly for δ(2)H along the hair shaft. Interpretation of the isotope data in corresponding segments of hair and nail for forensic purposes must consider particular variations, especially for chronological considerations.

Stable Isotope Characterization of Ammonium Metavanadate (2011)

Alan M Volpe, Michael J Singleton

This paper describes hydrogen (2H/1H), nitrogen (15N/14N), and oxygen (18O/16O) isotopic characteriza- tion of ammonium metavanadate (NH4VO3), a toxic industrial chemical (TIC). We analyzed nineteen high purity compounds obtained from nine suppliers, which show large ranges in trivariate stable isotope compositions, nearly 100-fold greater than analytical uncertainty. Covariation between d2H and d15N values indicates these ratios can be used to trace ammonia compounds, which are critical for the industrial purification of vanadyl ions and precipitation of ammoniummetavanadate crystals. d2H and d18O plot far from the Meteoric Water Line (MWL), and suggest materials and industrial processing may lead to decoupling of H and O isotopes. We show how stable isotope characterization is a valuable forensic tool that discriminates between NH4VO3 samples due to differences in source materials, modes of production, and facility location

Tamara S. Pilgrim, R. John Watling, Kliti Grice

The reputation of particular countries, and plantations within those countries, for the production of high quality tea means that these producers can ask a significantly higher price for their specific product than average. This leads to a temptation for unscrupulous producers to fraudulently label their product as coming from one of these areas to take advantage of this higher price. A simple method for the analysis and verification of the country and plantation of origin of tea would provide security to both tea growers and consumers and would largely stamp out this illegal activity. This paper details the use of complimentary organic and inorganic isotope techniques for the analysis of tea samples from Asia. The application of linear discriminant analysis of the isotope ratios and mineral concentrations permitted 97.6% correct classification of the tea samples using the following variables δD, δ13C, 49Ti, 53Cr, 59Co, 60Ni, 65Cu, 71Ga, 85Rb, 88Sr, 89Y, 93Nb, 111Cd, 133Cs, 138Ba, 139La, 140Ce, 141Pr, 153Eu, 203Tl, 208Pb and 209Bi.

Isotopic ratios to detect infringements of patents or proprietary processes of pharmaceuticals: Two case studiesJournal of Pharmaceutical and Biomedical Analysis (2008)

Because of the increasing problem of drug counterfeiting and the potential danger related as well as the economic losses involved, the pharmaceutical industry and the regulatory instances are interested in the development of anti-counterfeiting and patent protection methodologies. In this paper, the evaluation of measured isotopic ratios by means of explorative chemometric techniques was performed to distinguish groups in two data sets containing samples of acetyl salicylic acid and ibuprofen, respectively. The samples in the data sets originated from different countries and manufacturers. For both compounds a clear distinction of groups of samples could be obtained. These groups could be explained based on the origin of the samples, both geographically as well as based on the manufacturer. Hypotheses were formulated concerning the synthetic pathways of the molecules and they were linked to the groups obtained with the chemometric tools. ?? 2008.

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